Grinding mill



L. HOLLAND- LETZ anmnme IILL April 2, 1929.

Filed March 15; 1926 ZSheets-Sheet 1 L e/1y 022M! (5, F5 1/5? fig? April2, 1929. HOLLAND-LETZ GRINDING HILL 2 Sheets-Sheet 2 Filed larch 15,1926 Patented Apr. 2, 1929.

UNITED STATES LUDWIG HoLLANn-Lmz, or cit'ovv'n mm, I a g g FACTURINGCOMPANY, 11 conrdmrroiq or n'miANA.

mmm, lemma is me amenmmno MILL.

Application filed March 15, mo. Serial No. 94,000.

This invention relates to a grinding mill which is capable of reducingporous materials, but is particularly, adapted for fibrous material. r

One of the objects of the present invention is to provide an improvedform of grinding mill which is simple in construction and eflicient inoperation. r

A further object ofthe invention is to provide a novel and improved formof'grinding mill in which a single rotary member performs a plurality offunctions such as cutting the material being fed into the mill, feedingthe material thus cut and, grinding the material fed thereby.

A further object of the invention is to provide an improved form ofgrinding mill having a combination cutting, feeding and grinding memberwhich-is adapted ,to 00 operate with stationary portions of the mill.for recutting the material after the first cut- 7 ting operation. 1

A further object of the invention is. to provide an improved feedingmechanism in combination with a grinding mechanism whereby certainportions or ribs of the rotating menr ber co-opera-te with certainportions of the stationary member to alternately feed and cut thematerial during each cycle of operation of the rotating member. 7 r

A still further object of the invention is to provide a novelconstruction of a-grinding mill in which the tension or pressure betweenthe rotating member and the stationary buhr may be adjusted for grindingthe material into a fine, medium or course form.

These and other objects are accomplished by providing a construction'andan arrangement of the various parts in the manner here matter describedand particularly pointed out in the appended claims.

Referringto the drawings, Fig. ;1 is'a rear elevational view of myimproved grinding mill. I I 1 i j 1 Fig. 2 is a side elevational viewpartly section, taken on the lines 2.-2 in Fig. 1.

3 is a top plan view showing the construction of my improved form oirotary cutting, feeding and grinding member.

'Fig. dis a top plan view showing the con structionpt my stationary buhrwith-Jonly a portion. of the shear-ingor cutting projection shownthe'reon' r f 5 a partial tragmentary sec- .tional view taken on theline 5f 5-;m 1

showing a section of one of the cutter knives and its relativepositionto the stationary portrons of the mill adjacent the rotating memher orknife. n i

Fig. 6 is fragmentary cross sectional View taken on line 6'-6 in Fig. 1showing the constructionof the mechanism ,for adjusting thepressuretension between the grinding buhrs of the mill.

Fig. 7 is a reduced bottom plan view showing the construction of theadjusting collar. and indicator for varying the pressure or tensionbetween the grinding. buhrs.

I Fig. 8 isa side elevational View of the hearing sleeve which rotatablysupports the rotating member, and r Fig. 9 is an end elevational Viewshowing the construction of the bearing sleeve shown For the purpose ofillustration I have shown my improved grinding mill embodied in a handoperateddevice,- but it will of course be readily understood that apulley may be easily substituted for thecrzmk handle show-n in-thedrawing so as to make the same power operated.

In illustrating one embodiment of my invention I have shown the same ascomprising a frame portion 10-wlzlich is providedwith laterallyextending-ears or lugs 11,- which in turn, are provided withlongitudinally extending slots 12.5fm reception therein of bolts 13 forsecuring the mill to a stationary support which may be anysuitable tableor stand 14. The frame 10 is preferably circular-or disc-shaped in form;as shown at 15 and is provided with a concentrically at ranged rib asshown at 16 forreinforoingalnd strengthening the same. Extending aboutthe periphery of the disc shaped portion 15 and preferably atrightangles with respect thereto is an alnnnliit flange 17 so as to forma disc-shaped portion on the inner side of the frame. Extending atregular intervals on the, inner side/of the disc-shaped frame .ber 15are a plurality of cutter bars 18,:19, 20 and 21. The cutter bars 18, 19and 261mm constructed so that their inner port-ions :Eorm the arcs of acircleas shown at18'; lQ'nrid 20', respectively,; which be said tar-b6tangent to a cmnnmn ci rcle, concentric with the axis of'thedisc-shapedmember-15 have their outer ends in the form oia straightline, assho'wn at 18", 19 lmdQO"; NSF!!- tive'ly, is tangent to aconcentric with the first circle, but substantially larger than thefirst circle; These cutter bars extend inwardly from the base of thedisc-shaped member and have their cuttmgedges lymg in a plane which1sco1nmon to the inner edge 21 of the annularfiange 17. The cutter bar18 in cooperation with the cutter knife hereafter described forms "seeFig. 5.

the initial cutting mechanism for cutting the material as it is fed lntothe mill and the cutter bar's 19, 20 and 21 in co-operation with thecutter knives on the rotating member tangentwith a relatively smallcircle which would lie concentric with the axis of the discshapedmember15.'v Extending upwardly and outwardly at an angle with respect to thehorizontal is a hopper socket 22 which may have attached thereto ahopper 23. EX-

tending' below the hopper socket and preferably as a continuation of thehopper is an outwardly extending wall 24 which formsa pocket forreceiving and holding the material fed in through the hopper. Extendingthrough the'disc-like member 15 and communicating with the-pocket 24cand hopper is an 0pening25; This opening passes through the disc-portion15 and is in the form of substantially the shape of a heart, one edge ofwhich is bounded by the cutter bar 18 and the other edge of which isbounded by the curved portions 26.

One of the important features of my improvedgrinding millis'theprovisi0n of a novel construction of a rotating memberwhichperforms the function of cutting the material up and passing-thesame therethrough, thence feeding it into the shearing or grindingbuhrs. This mechanism comprises a rotating member 27 which is mountedconcentrically with the axis of the stationary frame member 10 androtatable with respect thereto. This member 27 is provided with a hubportion 28 in the center thereofand with a plurality ofcurvcd knives 29;These knives 29 are located on one-side of the rotating member 27 andare arranged at intervals of 120 degrees apart. -These knives 29 likethecutter bars 18, 19 and 20 have their inner ends in the form of arcsof circles which 1 might be saidto be tangent to relatively small circleconcentric with the aXisof rotation of the rotating member and theirouter ends in the-forinofarcs of relatively larger ing cuttcrbars'18, 19and 20 so that the outer portions of the cutter knives and c0operatingcutter 'bars rtss and convey the material inwardlytoward the axis of therotating memberso that the material is confined to a reducing ellipticalform where the material is finally sheared olf adjacentthe inner ends ofthe cutter members. It is of course understood that the cutting edges ofthe knives 29 move in a plane contacting with the plane of the cuttingedges of the bars 18, 19, 20

and 21, so as to effect a shearing action between these cutting members.The cutting knives 29 on the rotary member 27 are ranged so as to formpocket-s or chambers therebetween', through the medium of which thematerial is carried from cutter bar to cutter bar of the'franic 10, oneach cycle of operation of the rotary member for the re cuttingoperation of the material. .On each occasion that a pocket or chan'iberpasses the heart-like opening 25, in the frame 10, an additional supplyof material is added to the particular chamber. This operation iscontinuedthroughout the operation of the machine as material is beingfed into the hopper.

herotating'member 27 has three apertures somewhat irregular in shape asshown at 30 extending therethrough, and located adjacent the innercurved portions of the cutting knives 29 for permittingthe material asit is sheared between the cutting knives and'the cutter bars to passonthrough the rotating member from where it is fed by the cut by thecutting knives as shown in 5. Extending from the hub portion 28 and onthe side of the rotating member 2. up posite the knlves 29 are threemain feeding V ribs 33 which have broken extended portions shown at 33.These broken extended portions 33 as well as the outer portions of themain feeding ribs 33 as shown at a perform the alternate functions offeeding and shearing when co-operating with the co-acting ribs on thestationary member as will hereinafter be described; These main feedingribs 33 extend from adjacent the inner edges ofthe apertures 30 as shownat 34; to the outer periphery of the rotating member and are in the formof substantially cycloidal curves. .By this construc on it will bereadily seen that as the cutter knives 29 in co-operation f with thecutter bars on' the stationary frame inember'ltl cut the material theinclined por- 'tion 31 0f the'knives together with the inco ningmaterial forces 7 the material through the apertures 30 after-which theinner portio-n's of the feeding ribs engage the mat thus cu andin(co-operation with certain ribs K hereinafterdescribedforces thematerial toward the'outer periphery of the buhrs. Extending between themain feeding ribs 33 and located on the outer portion of the rotatingmember are a plurality of supplemental alternate feeding and shearingribs 35 which occupy a symmetrical position with respect to the mainfeeding ribs 33 so as to properly space these supplemental feeding andshearing ribs at substantially equal distances from each other. Thesesupplemental ribs 35 are preferably broken. Interpo'sed between each ofthe broken portions of these supplemental feeding and shearing ribs 35and also between the main ribs 33 and extended portion 33are-transversely positioned symmetrically arranged shearing ribs 36.These shearing ribs. 36 co-act with portions of the feeding ribs on thecomplimentary buhr to shear the material passing therebetweeli;Co-operating with the rotary member 27 and positioned concentricallywith the same is a stationary buhr 37. The stationary buhr 37 1is'pro'vided with ahub 38 and has four main feeding ribs 39 extendingfrom the hub 38 to the periphery, and are positioned in the reversedirection to that of the/main feeding ribs 33 on the rotating member 27.The.

main ribs 39 have broken extensions as shown at 39 and 40 which performthe alternate function of feeding and shearing when coacting with theco-operating ribs on the rotary member. These main feeding ribs 39 aresubstantially in the form of a cycloidal curve and are adapted toco-operate with the three main feeding ribs 33 on the rotary member 27for forcing and feeding the material cut by the knives in a directiontoward the periphery of the bnhrs to the grinding and shearing portionsof the'stationary and rotating members. In this connection, one of theimportant features of my improved grinding mill is the employment ofthree main feeding ribs on the rotating member which .co-operate withfour main feeding ribs on the stationary member so that only one of thefeeding ribs on the rotating member co-operates with its co-actingfeeding rib on the stationary member, thereby permitting only. one pairof co acting ribs to perform their function at one. time. In otherwords, by reason of having only three feeding ribs on the rotating memher and four feedingribs on the stationary member, these ribs alternatein their-co-oper ation with the corresponding stationary feedingribs forfeeding the material to the grind;

ing buhrs, thereby relieving the mill of an irregular excessive strainand the operator of intermittentburden of operating the machine thanwould be occasioned by having the numher of feeding ribs on the rotatingmember and the stationary member equal in number.

This construction of employing an unequal number of feeding ribs on therotary member and the stationary member, respectively,

progressively brings the co-acting ribs into ribs reversely curved 0nthe rotating member and stationary member, respectively, that as therotating member is revolved the action ofthe co-operating feeding ribsin crossin one another produces a mining action and forces or pressesthe material betweenthe V contiguous edges of the ribs in a directionoutwardly toward the periphery where it is engaged by the alternatefeeding andshean I ing ribs of the respective members. The stationarymember 37 is provided bet-ween each of the feeding ribs 39 with aplurality of syrn metrically. arranged su plemental alternate feedingand shearing ri 40. These ribs 40 are broken, as clearly shown in'Fig.4, and have interposed between the broken portions transverselyextending shearing or grindin-g ribs 41. I

It will be noted that when the alternate feeding and shearingpor-tionsef the main ribs33, as indicated eta and the extended portions 33 of themain feeding ribs 33 as well as p the supplemental feeding ribs 35' ofthe rotating member 27 are cooperatingwit-h the transverse ribs 41 ofthestationary member 37, a

shearing of the ribs 33 and extensions 33' as well as the supplementalfeeding ribs 35 co-' act with the corresponding feeding ribs 39,

39, 40 and 40 of the stationary member 37 a feeding or foreingofthematerial toward the periphery of the members is-taik-ingplaee. It willalso be noted that when the main fe -member 39, extensions 89 and40 asas the supplemental feeding ribs 40 co'act with thetransverse ribs 36%the rotary mam her a shearing of the material takes place. As previouslypointed out,'this action of feeding and shearing is alterriateand thefact that there are a series of seven ribs on the stationary member anda series of eight ribs on the rotary member causes such a relativedisplacement of the series of the ribs on the two faces that in eachsection there can only be one pair of the series actually shearing at atime, so that the'resistanee offered to the shearing ae tion is spreadout over the complete cycle of operation as to produce a practicallycontinuous resistance in the machine, instead of an intermittent one. Itwill also be noted that a further spreading out of the resistance to theshearing action is secured by the-fact that theeo -opera-ti I shearingribs of one buhrr m diverging alitt from the compel-sting feed; ing ribsof the other buhr' as to come into'" of this novel form of grinding buhrsee my The stationary member 37 is provided with a laterally projectinglug 42 which is adapted to engage a bracket The bracket 43 is provided'witha slot 44 on one side thereof for the reception of the lug 42 andon the other side thereof is provided with an aperture for the receptionof a bolt 45 which secures the bracket to a portion ofthe frame adjacentthe socket 22 This lug 42 on the stationary member 3 7 secures themember against rotation and at the same time permits the member 37'toadjust itself with respect to the rotary member. The rotating member 27is ,rotat ably supported on the main frame 10 by a bearing sleeve 46..The bearing sleeve 46 is provided with an enlarged circular portion 47which forms a shoulder 48 for engaging a finished portion 49 of therotating member 27. The sleeve 46 extends through the aperture 50 in therotating member 27 and also through the aperture 51 of the stationarymember 37..

The sleeve 46 is provided with a longitudinal extending bore 52. Formedin the enlarged portion 47 of the sleeve 46 and concentrical- 1yarranged with respect to the bore 52 is an annular recess 53 which formsa-seat for a compression spring The enlarged portion 47 of thesleeve 46is further provided with laterally projecting rectangular lugs 55 on theoppositesides thereof which are adapted to be seated in recesses or keyways 56 formed in the hub 57 of the frame member 10. These key-Ways 56engage the lugs 55 and prevent the sleeve 46 from rotation with respeetto the main frame 10.. The ma n frame member 10, rotary member 27 and.

stationary member 37 are held in their rela .tive operative positionsbya carriage bolt 58 which extendslthrough awasher 59 and sleeve 46 on oneend andthroughlian adjusting collax-'60 and thumb nut 61 on the otherend, the adjusting nut 61 being'in' threaded-engagement with thethreadedjportionof the bolt. It will be noted by referring to Fig. ,2 of

the drawing that the end of-the sleeve 46 asshown at 46 stops shortofthe washer 59 so that the sleeve 46 may move longitudinally a relativelyshort distance with respect to the stationary portions of the inill sothat the pressure of the spring 54 is brought to bear on the grindingsurf'acesof the buhrs. It will also be noted that tne finished portion.49 of the hub 28 of therotating member is sutlicient- 1y largetoengagethe innerfinished surface 57 'oflthe hub of the frame member-'10so as tolimit theretractile movement of the grmd-- in'g surfaceswithzrespect-to each other; i-lnother1important-feature of myimprovedgrinding'mill is-the provision of a novel means for permittingan'adjustment of the pressure between the surfaces of the therewith. inia bearmg boss 69 formed integral plurality of depressed recesses 62, 63and 64.

These recesses are arranged in a series of three corresponding recessesarranged about the bottom of. the collar at intervals 0-fabout onehundred and Itwenty'degrees apart. The recesses 62 are relativelyshallow with the recesses v63'and 64 at; graduated increasing depth sothat when theicollar is positioned in its operative position one set ofthe re cesses such as'62 engage co-Ton rating lugs 65. which registerwith the rece in the collar. When it is desired to gm a porous ornon-fibrous material; the collar is 'iositioned so that the shallowestrecesses 2 e or register with the lugs65 formed onjthe frame member 10,and when it is desired to reduce a relatively harder or fibrous materialthe recesses 63 engage or register with the lugs 65, and whenit isdesired to reduce exceptionally hard, fibrous or wetmaterial the collaradjusted so that the deepest recesses 64 engage or register with the lug65 of the frame member 10. In order to facilitate this adjustment 1 haveprovided an indicator as shown at 66 which will aid the operator inproperly adjusting the mill'by letting the in dicator 66 on the collarregister with mar rs A, B and C, indicating light, intermediate andheavy spring pressure on the surfaces of the grinding buhrs.

From the above will be seen that by permitting the collar .60 to beadjusted inwardl withres acct tothe frame and ad 'ustin thumb l J e inut-61' the pressure on the sprin 54 v 7 correspondingly increased,there oy proportionally increasing the pressure between the grindingsurfaces of the buhrs. In other words by increasing the spring pressure,the sleeve 46: entirely transmits this increased pressure entirely uponthe grinding surfaces of thehuhrs so that at the time sufficientpressure will be maintained on the cutter so asto retain them in propercutting relation, whereby unusual tough, wet or librous materials may bereadily reduced.

In the drawings I haveshown the actuating. means comprising a crankhandle 67 which has a stub shaft 68 formed integrally The stubshaft 68is journalled ly with is secured against displacen'ient from the bearingthe frame member 10.. v The crank 6! bossv 69 by a cotter pinTO. Securedadjacent iii) the-gear teeth 72 formed integrally with and on theperiphery of the rotating member 2?. 'From 'the above 1t will be seenthat when the material is fed in through the hopper 28 it passes intothe pocket 2-1 adjacent the socket 22 and passes through the heartshapedopening 25 and as the revolving knives 29 are revolved in the directionindicated by the arrow in Fig. 1 to a position where they co-operatewith the cutter bar 18, the material is conveyed inwardly toward theaxis of the rotating member where it is confined between the cuttingmember in the form .of an ellipse when it islinally cut into relativelylarge particles, after which they are again recu't by the knives 29 andwent ting bars 19, 20 and 21, and as the material is continued to be fedit is forced through the opening 30 in the rotating member 29 and by theaction of the inclined portions 81 of the knives, the material isforced'and fed to a position where it is engaged by the feeding ribs 33of the rotating member 27 in co-operation with the feeding ribs 39 ofthe nonrotating member or stationary buhr 37 and by reason of thereversely curved feeding ribs of these respective members the materialis forced outwardly to the alternate feeding, and sheering ribs adjacentthe periphery of' these members where it is ground to the reduced formas previously described.

While in the above specification I have described one embodiment of myinvention, it will of course be understood that the same is capable ofmodification and that modification may be employed without departingfrom the spirit and scope of the invention as expressed in the followingclaims.

What I claim as my invention and desire to secure by Letters Patent is:i

1. A grinding mill comprising a frame and a rotary member journalled onsaid frame having cutting means on one portion thereof, and separatefeeding and grinding means on an opposite portion thereof.

2. A grinding mill comprising a frame'and rotary member journalled onsaid frame having cutting and re-cutting means on one side thereof, andfeeding and grinding means on V the other side thereof.

, 3. A griding mill comprising a frame and a rotary member journalledonsaid frame having cutting means on one side thereof and feeding andgrinding means on the other side thereof. c

4. A grinding mill comprising a frame and a rotary member journalled onsaid frame having cutting means on one side thereof, and feeding andgrinding means on the other side thereof, there being an aperture insaid rotary member adjacent said cutting means through which thematerial passes to said feeding and grinding means.

5.. A grinding mill comprising a frame and a rotary member journalled onsaid frame having cutting means on one side thereof, a d f edi andselies mean on the ther d th r i her e eean aperture in said rotarymember adjacent the axis thereof through which the" material passes tosaid'feeding' and grinding means.

6. A grinding mill comprising a frame and a rotary member mounted onsaid frame having a plurality of spaced apart knives on one sidethereof, and feeding and grinding means on the other side thereof, therebeing a plurality of apertures in said rotary member adjacent saidknives through which the cut material passes to said feeding andgrinding means; i i

7. A grinding mill comprising a frame and a rotary. member mounted onsaid frame having a plurality of spaced apart knives on one sidethereof, and feeding and grinding means on the other side thereof, therebeing a plurality of apertures in said rotary member adjacent the axisof said rotary member through which the cut material passes to saidfeeding and grinding means.

8. A grinding mill comprising aframe and a rotary member mounted on saidframe having a curved knife on one side thereof, and feedin and grindingmeans on the other side thereo there being apertures in said rotarymember adjacent said curved knives through which the cut material passesto said feeding and grinding means. 7

9. A grinding mill comprising a frame and a rotary member mounted onsaid frame having a plurality of spaced apart curved cutting knives'onone side thereof, and feeding and grinding means on the other sidethereof, there being apertures in said rotar member adjacent said curvedknives through which the cut material passes to said feed- .ing andgrinding means.

10. A grinding mill comprising a frame, a cutter bar-mounted on saidframe, a rotary member journalled on said frame, a cutter knife carriedon one side of said rotary memher and co-operating with said cutter barfor cutting the'material fed into said mill, and

means carried on the other side of said rotary member for feeding andgrinding the material cut by said knife and cutter bar.

:11. In a grinding machine, the combine,"

tion of a air of buhrs,-each having a plurality of ftieding ribsextending from adjacent the center thereof to the periphery, and aplurality of angularly disposed grinding ribs, whereby the feeding ribson one buhr co-operate with the feeding and grinding ribs onthe otherbuhr, to alternately feed and gpiad the material passing therebetween,

one of said buhrs having cutting means on one face thereof, for cuttingmaterial previous tohgviflg it ground on the other fa thereof.

13, In a grinding machine, the combination of a pair of buhrs,eachhaving a; plurality of feeding ribs, certain of said ribs weedingrom fl iacent the mm thereof to the periphery, and a pluvahty'of gmndangribs positioned transversely with respect to said feeding ribs wherebythe feeding ribs on one buhr co-operate with the feeding and grindingribs on the other buhr to alternately feed and grind the materialpassing there between, one of said buhrs having a plurality of knives onthe other face thereof.

13. In a grinding machine, the combination of a pair of buhrs, each buhrhaving a plurality of feeding ribs, certain of said ribs extending fromadjacent the center of the buhr to the periphery thereof, there being anaperture through one of said buhrs, adj acent said last named rib, and apluralityof grinding ribs positioned transversely wlth respect to saidfeeding ribs whereby the feeding ribs on one of said buhrs co-operatewith the feeding and grinding ribs on the other of said buhrs toalternately feed and grind the material passing therebetween, the buhrhaving the aperture therein being provided with a plurality of cuttingknives on one v face thereof.

14-; Ina grinding machine, the combination of a pair of buhrs, eachhaving a plurality of "feeding ribs extending'from the center thereof tothe periphery, there being a greater numberof feeding ribs on one ofsaid buhrs than on the other, a. plurality of grinding ribs positionedtransversely with respect to said feeding ribs, whereby the feed-, ingribson one of said buhrs'co-operate with the feeding and grinding ribson the other to alternately feed and grind the material passing betweenthe buhrs, one of said buhrs being provided with a plurality of kniveson one side thereof. 7

15. A grinding mill comprising a frame, a rotary member journalled onsaid frame, said, rotary member having cutting mechanism on one sidethereof and grinding mechanism on the other side thereof, a stationarymember mounted on said frame and cooperating with the grinding mechanismon said ating with the grinding rotary member, and means whereby thepressure between the grinding surfaces of said menibers may beproportionately increased over the pressure on said cutting mechanism.

16. Agrindingmill comprising a frame,

a rotary member journallcd on said frame,

said rotary member having cuttingmechw nism on one side thereofand'grinding mechanism on the other side thereof, a stationary membermountedon said frame and co-opermechanism on said rotary member, andresilient means whereby the pressure between the grinding surfaces ofsaid members may be proportionately increased over the pressure on saidcutting mechanism. 5

17. A grinding millcomprising a frame, a rotary member journalled onsaid frame, said rotary member having cutting mechanism on one sidethereof and grinding mechanism on the other side thereof, a stationarymember mounted on said frame and cooperating with the grinding mechanismon said rotary memher, and means operatively connecting the axes of therotary and stationary members together whereby the pressure between thegrinding surfaces of saidmembers may be proportionately increased overthe pressure on said cutting mechanism.

18.. A grinding mill comprising a frame, a rotary member journalled onsaid frame, said-rotary member having cutting mechanism on one sidethereof and grinding mechanism on the other side thereof, a stationarymember mounted on said frame and co-oper ating with the grindingmechanism on said rotary member, and means movable axially of saidmembers whereby the pressure between'the grinding surfaces of saidmembers may be proportionately increased over the pressure on saidcutting mechanism.

19. A grinding mill comprising a frame, a rotary member journalled onsaid frame, the

rotary member having cutting mechanism on one side thereof'and grindingmechanism on the other side thereof, .a stationary member mounted onsaid frame and co-operatmg with the grinding mechanism on said rotarymemother side of the rotary member, a stationary member mounted on saidframe and'having grinding ribs co-operating with the ribson said rotarymembers, and adjustable spring means whereby the pressure between thegrinding surfaces of said members may be varied. a I I 21. A grindingmill comprising a frame, a cutter bar carried by said frame, a rotarymember journalled on said frame having a cutter knife mounted on oneside thereof and. co-operating with'the 'cutter bar on said frame, aplurality of grinding ribs on the other side of the rotary member, astationary member mounted on said frame and having grinding ribsco-operating with the ribs on said rotary members, and means includingmember and an'adjustable tension spring for lit) proportionatelyincreasing the pressure on the grinding surfaces of said rotary andstationary'members. r

22. A grinding'mill comprising a frame, a plurality of cutter barscarried by said frame,.a rotary member journalled on said "frame, and aplurality ofcutter knives carried by said rotary member, there being adifferent numberof cutter knives on said rotary member than the numberof cutter bars on said frame whereby cutting action of the variouscutting members will be consecutive rather than simultaneous.

23. A grinding mill comprising a frame, a plurality of curved cutterbars carried by said frame, a rotary member journalled on said frame,and a plurality of cutter knives carried by said member, said cutterknives being curved in a reverse direction from the direction of thecurvature of said cutter bars.

24. A grinding mill comprisinga frame, a plurality of curved cutter barscarried by .said frame, a rotary member journallcd on said frame, and aplurality of cutter knives carried by said member, said cutter knivesbeing curved in a reverse direction from the direction of the curvatureof said cutter bars, there being a different number of cutter knives onsaid rotary member than the number of cutter bars on said frame wherebythe cutting action of the various cuttingmembers will be consecutiverather than simultaneous. 7

25. A grinding machine comprising a frame, a plurality of spaced apartcutter bars mounted on said frame, said cutter bars having their innerportions in the form oft-he are of a circle tangent with a small circleconcentric with the axis of the frame and outer portions of said barsextending on a straight line tangent with a relatively larger circleconcentric with the first circle, a rotary member journalled on saidframeand having a plurality of spaced apart knives cooperating with saidcutter bars and having their inner ends in the form of the arcs ofcircles tangent with a circle concentric with the axis of the rotarymember and their outer ends the arcs of relatively larger circles,whereby the material fed into said machine is conveyed inwardly by theaction of the knivesand cutter bar and compressed in the form of anellipse and then sheared by the cutting members. V

26. A grinding mill comprising a frame, a rotary member journalled onsaid frame having a cutter knife on one side thereof, there being anaperture adjacent said cutter knife,

and conveying means on the other side of the rotary member extendingfrom adjacent said aperture. I

27. A grinding mill comprising a frame, a rotary member journalled onsaid frame and having a plurality of cutter knives on one side thereof,there being apertures adjacent said cutter knives, and conveying meanson the other side of said rotary member extending from adjacent saidapertures.

28. A grinding mill comprising a frame, a rotary member journalled onsaid frame and having a plurality of cutter knives on one side thereof,there being a plurality of apertures arranged eccentrically of the axisof said rotary member, and conveying means on the other side of saidrotary member extending from adjacent said apertures.

29. A grinding mill comprising a frame, a rotary member journalled onsaid frame, cutter bars carried by said frame, a plurality of s acedapart curved cutter knives carried y said rotary member and co-operatingwit-h said cutter bars for cutting the material passing therebetween,there being apertures adjacent the knives in said rotary member, andconveying ribs on the rotary member on the side opposite the knives forconveying the material cut by said cutting members.

30. A grinding mill comprising a frame, a

rotary member journaled on said frame, having a plurality of cuttingknives on one side thereof, forming material carrying chamberstherebetween, there being an aperture in said rotary member throughwhich material passes, and conveying means on the other side of saidrotary memberadjacent said aperture.

31. A grinding mill comprising a frame, a rotary member journaled onsaid frame, having a plurality of cutting knives on one side thereofforming material carrying chambers therebetween, there being a pluralityof apertures located adjacent the axis of said rotary member and aplurality of conveying ribs located on the other side of said rotarymember adjacent said apertures.

In testimony whereof I have signed my name to this specificatioin onthis 8th day of March, A. D. 1926.

LUDWIG- HOLLAND-LETZ.

